IMO this would be a logical move for US and could provide significantly more high yield international PHL feed and expansion, with little competition from AA - unlike CO and UA does (will) in Star. Additionally, US could hypothetically release PHL-LHR to BA and sell the slots for $80M or so. Obviously there could be concerns (particularly from BA) regarding service standards.
http://www.usatoday.com/travel/columnist/g...-alliance_N.htm
http://www.usatoday.com/travel/columnist/g...-alliance_N.htm